A principal strategy currently employed in imparting odors to consumer products is the admixing of the fragrance directly into the product. There are, however, several drawbacks to this strategy. The fragrance material can be too volatile and/or too soluble, resulting in fragrance loss during manufacturing, storage, and use. Many fragrance materials are also unstable over time. This again results in loss during storage.
In many consumer products it is desirable for the fragrance to be released slowly over time. Micro-encapsulation and inclusion complexes with cyclodextrins have been used to help decrease volatility, improve stability and provide slow-release properties. However, these methods are often unsuccessful. In addition, cyclodextrins can be too expensive.
Precursors for the delivery of organoleptic compounds, especially for flavors, fragrances, and masking agents, are disclosed in EP-A 0 936 211. This delivery system releases one or more odoriferous compounds upon exposure to light and/or UV irradiation. Using this system in various consumer products leads to a prolonged perception of the fragrant compound(s) to be released.
WO 99/60990 discloses fragrance precursors which release fragrant alcohols, aldehydes, or ketones upon exposure to light. Perfuming compositions containing these fragrance precursors can be used in various consumer products such as detergents, fabric softeners, household products, hair-care products etc.
Many fragrant compounds with odors accepted by the public are lactones. In fragrance compositions these lactones play an important role in imparting the fruity aspects of a perfume. Fragrant lactones are prone to undergo hydrolysis, especially in alkaline products such as detergents, into the hydroxy fatty acids salts, which exhibit enhanced water solubility and to a great extent are washed away in the washing/cleaning process. This results in considerable loss of perfume and in particular the fruity notes. Lactones, especially the aliphatic low molecular weight lactones, are rather volatile compounds. Furthermore, they are water soluble and are, therefore, lost to some extent during the washing/rinsing cycle if introduced directly into detergents.
Therefore, these lactones are of limited use in laundry products, especially detergents.
Cyclic acetals of the formula IV where R8 to R15 are all H, and R16 is the residue of an organic alcohol, which serve as a protective group for alcohols have been described. (Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.; John Wiley and Sons: New York, 1991, p31.)
Certain compounds of formula I are known. 
A compound of formula I where n is 1, R8 is C6, and R1 to R7 as well as R9 to R15 are H has been used as an intermediate in a natural product synthesis. (Dixon et al., Synlett, 1998, 1093-1095.)
A further compound is used as a substrate in a diastereoselective reduction, wherein the cyclic acetal is used as a chiral auxiliary (e.g. Noe et al., Angew. Chem. 1988, 100, 1431-1433).
It is known that phenacyl glycosides undergo a Norrish Type II photoreaction leading to gluconolactones and the corresponding aryl ketone (Brunckova and Crich, Tetrahedron, 1995, 51, 11945-11952). However, it has not been described or suggested to use such phenacyl acetals as fragrance precursors, which are capable of releasing a fragrant ketone and a fragrant lactone over a prolonged period.